Thoracic Wall and Diaphragm Flashcards
What is the thorax?
Area between neck and abdomen
What does the thorax consist of?
- Thoracic cage (ribs), thoracic wall (muscles)
What is contained in the thoracic cavity?
- Heart
- Great vessels
- Lungs
- Trachea
- Oesophagus
Classify the manubriosternal joint
- Secondary cartilaginous joint
- Symphysis
At what level is the sternal angle found?
- T4/5
Classify the 12 ribs
- 7 true
- 3 false
- 2 floating
Describe thoracic vertebrae
- Heart shaped body
- Transverse process blunt (ribs)
- Spinous process angled down
- Only level below vertebrae
What is the clinical relevance of T2/3?
- Jugular notch
What is the clinical relevance of levels T4/5?
- Sternal angle
What is the clinical relevance of T9?
- Xiphisternal joint
What is the clinical relevance of L3?
- Costal margin
Describe the structure of a typical rib (3rd to 9th)
- Head- Capitulum
- 2 facets- superior (attaches to inferior facet or superior vertebra)
- Tuberculum articulates with transverse process (Facet)
- Head end of rib articulates with vertebrae (above and below)
Classify the costovertebral joint
Plane synovial joint
Classify the costo-transverse joint
Plane synovial joint
Classify the sternoclavicular joint
- Double synovial joint (2 joint cavities)- Saddle joint
- Surrounded by anterior sternoclavicular ligament
Describe the interclavicular ligament
- Join two clavicles together (medial)
Describe the costoclavicular ligament
- Between the clavicle and first rib
Classify rib 1
Syndchondrosis joint
Classify ribs 2-7
- Synovial chondrosternal joints
- Between cartilage and sternum
Describe the arterial supply to the ribs
- Thoracic aorta–> posterior thoracic artery –> segmental intercostal arteries
Describe the arterial route that leads to diaphragm supply
- Subclavian arteries
- Internal thoracic artery (either side of sternum to costal margin)
- Anterior thoracic artery
- Musculophrenic artery branch (supplies diaphragm)
Where is the anastamoses in the arterial supply?
- Anterior and posterior intercostal arteries anastamose
Which areas do the segmental intercostal arteries not supply?
Intercostal spaces 1 and 2
Describe the arterial supply of 1st and 2nd intercostal spaces
- Subclavian artery
- Costocervical trunk
- Supreme intercostal arteries
- 1st and 2nd intercostal arteries
Describe the venous drainage of the diaphragm
- Musculophrenic vein (diaphragm)
- Anterior internal thoracic vein (both sides of sternum)
- Brachiocephalic veins
Which veins drain the thorax
- Posterior intercostal vein:
- Accessory hemiazygos vein
- Hemiazygos vein
- Azygos vein
What does the accessory hemiazygos vein drain?
- Superior half of left thorax
- Then travels across vertebrae (T8/9) and drains into azygos vein
What does the hemiazygos vein drain?
- Inferior half of left thorax
- Travels across vertebrae (T8/9) and drains into azygos vein
Where does the posterior right intercostal vein drain?
- Azygos vein
What happens to the azygos vein at the sternal angle?
- Over primary bronchus
- Drains into superior vena cava
Which veins drain the 1st intercostal vein and where do they drain into?
- Right and left SUPREME intercostal veins
- Drain into brachiocephalic vein
What does the superior intercostal vein drain?
- Drains 2nd, 3rd and 4th intercostal spaces
- 2nd, 3rd, and 4th posterior intercostal veins drain into this vein
Where do the superior intercostal veins drain into?
- On the left into accessory hemiazygos vein + brachiocephalic vein
- On the right into the arch of azygos vein- into the superior vena cava
What are the names of the lymph nodes on either side of the sternum?
- Parasternal lymph nodes
What is the name of the lymph nodes on either side of the vertebral column?
- Paravertebral lymph nodes
Where is the thoracic duct found?
- Midline of anterior face of vertebrae- from cisterna chyli
What happens to the thoracic duct at the sternal angle?
- Left and drains into angle between and left jugular vein
From what levels do the posterior and anterior intercostal nerves arise from?
- T1-12
- Sympathetic trunk
- Around each individual rib
Where is the endothoracic fascia found?
- Between intercostal muscles and parietal pleura
When does posterior intercostal become anterior intercostal?
Anterior side of thorax
Describe the direction of the external intercostal muscle
- Hands in pockets
Describe the direction of internal and innermost intercostal muscles
- Hands to chest
What nerves supply the external, internal and innermost intercostal muscles?
- Intercostal nerves
What is the location and function of the transversus thoracis muscle?
- Inside thorax - attaches to sternum
- Accessory muscle for respiration
Describe quiet inspiration
- Diaphragm contracts
- External intercostals contract
- Thoracic volume increases
Describe quiet expiration
- Inspiratory muscles relax
- Rib cage descends
- Elastic recoil of lungs
- Thoracic volume decreases
Describe forced inspiration
- Scalenes, sternocleidomastoid muscles and pectorals contract
Describe forced expiration
- Accessory- abdominal muscles (rectus abdominis and obliques)
Where is the internal intercostal membrane found?
- Near vertebra where there is no muscle in the space
Where is the neurovascular bundle found?
- In costal groove
Describe the order of nerves and vessels in the neurovascular bundle?
- Superior to inferior:
- Vein, artery and nerve
Why is the right dome of the diaphragm higher than the left?
- Liver pushing up underneath
Describe the visceral pleura
- Shiny surrounding lungs
Describe the parietal pleura
- Shiny attached to ribs
Where are both pleura also present?
- Fissures of the lung
What nerve supplies the diaphragm?
- Phrenic nerve
C3, 4, 5 keeps the diaphragm alive!
Describe the arterial supply of the diaphragm
- Intercostal arteries supply periphery of diaphragm
- Musculophrenic artery supplies centre of diaphragm (front half)
- Pericardiophrenic artery from intercostal artery (runs with phrenic nerve, not seen)
- Superior and inferior phrenic artery
Describe the venous supply of the diaphragm
- Musculophrenic veins
- Inferior phrenic veins (no superior) under diaphragm
